1. Field of the Invention
This invention relates to a color image forming apparatus and method, and particularly to a color image forming apparatus and method of the electrophotographic type used as a copying apparatus or a printer.
2. Related Background Art
Heretofore, a color image forming apparatus having an intermediate transfer member has not made the cleaning time for the intermediate transfer member variably controllable by image forming conditions, but has supposed the worst case thereof and determined the cleaning time, and has executed cleaning in accordance with the determination. Particularly, in a printer which permits the mixed presence of color modes, i.e., the mixed presence of full color mode printing and monochromatic mode printing in the middle of continuous printing, the color condition commanded by a host computer for controlling the printer is indefinite. So, as regards the amount of cleaning of the intermediate transfer member, the maximum number of prints in the continuous printing by the full color mode is naturally supposed as the worst case, and also in the color mode and the number of prints, the effect of cleaning is reliably displayed to thereby secure the quality of the next printing.
However, in the printer according to the prior art which permits the mixed presence of the full color mode and the monochromatic mode in the middle of continuous printing and supposes the worst case to thereby control the cleaning time, it is necessary for an operator to wait for the cleaning time determined in the worst case until the next printing whenever cleaning is executed even in the middle of monochromatic printing. Also to the printer, realistic life taking the conditions of actual use into account cannot be set and in the choice of parts, it is necessary to excessively set the required life period. Also, depending on the cleaning method, noise is created and even during the printing by the monochromatic mode which originally could be short, noise is created for a long cleaning time corresponding to the printing time by the full color mode.
It is the object of the present invention to provide a color image forming apparatus and method of the electrophotographic type which can determine the cleaning time with the conditions of actual use of monochromatic mode printing and full color mode printing taken into account.
The present invention which achieves the above object relates to image forming apparatus for forming the images in the monochromatic mode and the full color mode by an electro-photographic system. The apparatus has means for forming a toner image on an image bearing member in a predetermined color mode, transfer means for transferring the toner image to a transfer member, cleaning means for removing any toner remaining on the image bearing member after the transfer, color mode detecting means for detecting the kind of a selected color mode, and determining means for determining the time for the cleaning means to clean the image bearing member on the basis of the detected kind of the color mode. The determining means sets the execution time of the cleaning means shorter for the monochromatic mode than for the color mode.
Also, the present invention relates to a color image forming method of forming the images of the monochromatic mode and the full color mode on an image bearing member by the electro-photographic system. The method has the step of forming a toner image on the image bearing member in a predetermined color mode, the transferring step of transferring the toner image to a transfer member, the cleaning step of removing any toner remaining on the image bearing member after the transfer, the color mode detecting step of detecting the kind of the selected color mode, and the determining step of determining the time for the cleaning means to clean the image bearing member on the basis of the detected kind of the color mode. The determining step sets the execution time of the cleaning means shorter for the monochromatic mode than for the full color mode.